Hydrocyclone pulp cleaner

ABSTRACT

This invention is a hydrocyclone pulp cleaner having a single conical shell divided into two separation chambers by an improved baffle construction which materially increases the efficiency of separation thus increasing the percentage of acceptable material and reducing the percentage of bottom reject material. The dividing baffle is constructed to provide an inlet for the material entering upper portion of the bottom chamber in a substantially tangential direction at the upper portion of the side wall of the lower chamber and in the form disclosed the size of the inlet opening is adjustable. The baffle is also designed to retard the flow of pulp from the top to the bottom chamber and is provided with a central discharge to remove the acceptable material from the bottom separation chamber upwardly through the baffle.

United States Patent [1 1 Zemanek HYDROCYCLONE PULP CLEANER [7 5]Inventor: Rudolph Zemanek, lntl Falls, Minn.

[73] Assignee: Boise Cascade Corporation, Boise,

Idaho [22] Filed: Feb. 22, 1971 [21] Appl. No.: 117,566

FOREIGN PATENTS OR APPLICATIONS 695,347 8/1953 GreatBritain ..209/14 4 IOct. 9, 1973 OTHER PUBLICATIONS Frykhult, German Printed Application No.2,013,499, Pub. 10/15/70.

Primary Examiner-Frank W. Lutter Assistant Examiner-Ralph J. Hill .iwrxfl 9112 11; Adams bers by an improved baffle construction whichmateriallyhicreases the efficiency of separation thus increasing thepercentage of acceptable material and reduc ing the percentage of bottomreject material. The dividing baffle is constructed to provide an inletfor the material entering upper portion of the bottom chamber in asubstantially tangential direction at the upper portion of the side wallof the lower chamber and in the form disclosed the size of the inletopening is adjustable. The baffle is also designed to retard the flow ofpulp from the top to the bottom chamber and is provided with a centraldischarge to remove the acceptable material from the bottom separationchamber upwardly through the baffle.

9 Claims, 3 Drawing Figures PATENTEDUCT "9197s I 3.764.005

I N VENTORv R0001 Pl/ Z'MAA/EK WWW lrraxwey HYDROCYCLONE PULP CLEANERThis invention is particularly adapted to produce efficient separationwith high capacity pulp flow and although the cleaner herein disclosedis related to the prior art cleaner disclosed and claimed in U. S.Letters Patent No. 3,425,545 of which the present inventor was aco-inventor, thepresent cleaner has proved considerably more efficientfor use with high volume flow than was the cleaner disclosed in saidprior art patent.

Pulp used in the paper making process must be highly refined in order toproduce finished paper of acceptable strength and appearance. Impuritieswhichmust be removed from the paper pulp during the refining process maybe classified generally in two categories. One type of impurity ismaterial ofa heavier density than the density of the acceptable finalpulp product} and consists of coarse material suchas bark anddirt, andis generally referred to by theterm specks. The heavier specks areremoved at the bottom of hydrocyclone cleaners. In present pulp cleaningprocedures it is normal to process the paper pulp through a stage ofcleaning in which a plurality of high capacity pulp cleaners clean thepulp and pass an acceptable fraction on for further proccessing andpaper making. However, in the prior art the acceptable fraction of pulpwhich is rejected with the impurities classified as specks is so largethat a second stage of cleaning process is used on the rejected speckmaterial from the first stage of the hydrocyclone cleaning system.

The present invention eliminates the necessity for a two stage cleaningprocess by improving the efficiency of the cleaning operation and speckremoval in a sin- .gle stage operationr This invention is a two-chambersingle stage hydrocyclone pulp cleaner with a baffle disposed betweenand connecting the two chambers and in which the rejected pulp does notcontain acceptable fibers which must be reclaimed. The first chamber isa large conical chamber having a main feed pulp inlet in the sidethereof and a discharge outlet at the top thereof forthe acceptablepulp. The first chambertapers downwardly to the baffle which serves toconnect the first chamber with the second smaller conical chamber. Thepulp travels helically downwardly in the first chamber with the heavyimpure particles tending to accumulate along the peripheral edges of thefluid flow near the side wall of the chamber. The acceptable pulp iscirculated towards the central area of the chamber by the centrifugaleffect of concentrating impurities at the outer wall and as the chamberis tapered downwardly the volume of fluid flow is restricted so that theacceptable pulp material in the central region is forced'upwardly alongthe central vertical axis of the chamber and out the centrally locateddischarge outlet at the top thereof. The heavier unacceptable fibersconcentrated at the outer edges of the fluid flow are permitted totravel through the baffle whereas the acceptable pulp materials in thecenter of the fluid flow are not allowed to travel through the baffle.

The second conical hydrocyclone chamber receives only the pulpcontaining the heavier impure particles and will further refine andseparate these heavier impurities from the pulp. The baffle separatingthe first chamber from the second chamber is designed to allow only theperipheral rotating fluidin the first chamber to pass spirallydownwardly into the second chamber and which will cause the refinedacceptable material in' the first chamber to be directed upwardlytowards the acceptable pulp discharge outlet therein. In the embodimentof my invention illustrated herein the baffle. consistsof a cylindricalside wall closed at the upper end and open at the lower end which ismounted on an annular attachment flange with the axis'of the cylindercoinciding with the vertical central axis of the conical chambers. Atangentially directed. slot is cut through the wall of the cylinderparallel to the axis thereof. The slot is cut in the direction of fluidflow so that the rotating heavier pulp passes into the lower chamberwhile maintaining its rotationalmovement. The size of the slot may beeasily adjusted in the form of the baffle disclosed.

One of the results achieved by my invention is the reduction in thequantity of bottom reject material to a volume which may be effectivelyconsidered waste without the necessity or re-claiming acceptable fiberscontained therein. This improvement in reducing the percentage of bottomrejects therefore eliminatesthe requirement of an entire second stage ofhydrocyclone cleaning of the bottom rejected material.

It is accordingly an object of this invention to produce an improvedsingle stage hydrocyclone pulp cleaning apparatus which will improve theoverall efficiency of removing reject particles from a feed pulpmaterial.

It is a further object of this invention to provide a pair of axiallyarranged conical separation chambers separated by an inverted cup-shapedbaffle having a gener ally cylindrical side wall portion which isprovided with an inlet opening to permit the heavier materialcirculating around the wall at the bottom of the upper chamber to passinto the lower chamber along the outside upper wall portion of saidlower chamber, the acceptable material passing upwardly through thechambers and the reject material being discharged through an opening inthe bottom of the lower chamber, said two chambers producing materiallyimproved separation of the pulp material into the accepts and rejects.

These and. other objects and advantages of this invention will beapparent from the following description made in connection withaccompanying drawing wherein like reference characters refer to similarparts throughout the the several views, and in which:

FIG. 1 is a semi-diagrammatic cross-sectional view of a hydrocyclonecleaning apparatus according to my invention;

FIG. 2 is a fragmentary central vertical sectional view of theseparation baffle portion hydrocyclone apparatus shown in FIG. 1; and,

FIG. 3 is a cross-sectional view thereof taken substantially along lines33 of FIG. 2.

In the embodiment of my invention shown in the fig ures reference number10 generally designates the entirety of a hydrocyclone cleaningapparatus. The apparatus consists of an inlet chamber 12., a large firstconical hydrocyclone chamber 14, and a second smaller hydrocyclonechamber 16 connected to the first at the bottom end thereof. Chamber 16has a bottom reject orifice 17. The taper of the second conical chamberneed not necessarily be of the same proportion as that of the firstchamber, as is shown in this embodiment of my invention. Fluid flowingfrom the first hydrocyclone chamber tothe second must pass through abaffle element 18 which will be more fully explained later. A pipe 20 isconnected to a feed pulp supply for the hydrocyclone pulp cleaningsystem. A valve 22 in pipe 20 is used to regulate the pressure and rateof flow of fluid pulp into the hydrocyclone cleaner. An inlet pipe 24extends from the valve 22 so that paper pulp enters the inlet chamber 12through a tangential inlet opening 26 which will cause the incoming pulpto rotate in the cleaning apparatus 10. A discharge outlet 28 isprovided for acceptable fiber separated from impurities in the firstlarger conical'separation chamber 14. This outlet 28 may extend, as inthis embodiment of my invention, through the inlet chamber 12 and outthe top thereof. A valve 30 is provided in the acceptable fiber outlet28 in order to control the back pressure of fluid in the firsthydrocyclone chamber. As will be explained further, it is necessary toregulate the fluid pressures within the hydrocyclone chambers toestablish the proper fluid flow characteristics for the most accept ablepulp cleaning efficiency.

An outlet pipe 32 is provided, extending through the baffle 18, todischarge acceptable pulp from the second small conical hydrocyclonechamber 16. As shown in this embodiment of my invention, the pipe 32 mayextend centrally through the central vertical axis of the largerhydrocyclone chamber 14, into the acceptable discharge pipe 28 andthrough the side thereof at a bend therein, as at 34. A valve 36 isprovided in the pipe 32 in order to control the fluid flow in the pipeand to establish the proper back pressure characteristics in thehydrocyclone cleaning chamber 16 for the most acceptable cleaningcharacteristics and operation within the chamber. The back pressure inchamber 16 would not be as easily controlled and adjusted if the pipe 32and valve 36 were eliminated and the baffle 18 had a central openingdirectly into the larger chamber 14.

The present embodiment of my invention includes a baffle member 18separating the first and second conical hydrocyclone separationchambers. The baffle required to make this invention operative, as hasbeen previously described, should be of a type allowing the fluidflowing tangentially near the peripheral side wall of the upper conicalchamber 14 to flow into the lower chamber 16 and continue to circulatespirally downwardly in the second chamber as in the first. Theembodiment of my invention, herein illustrated, employs an invertedcup-shaped baffle 18. The side wall portion 18a of the baffle 18 isgenerally cylindrical with a plate 18b at the upper end thereof and hasan opening therein for connection with pipe 32 to discharge acceptablepulp from the lower conical hydrocyclone separating chamber 16. Thelower end of the side wall 18a is secured to an annular mounting plate180 which is suitably attached at the lower end of the upper chamber 14.Through the wall 18a there is a slot 18d which in the form shown extendsthe longitudinal length of the cylinder and which, as shown in FIG. 3,is tangentially directed so that the pulp portion circulating around theouter portion of chamber 14 in a generally downwardly extendingdirection will be directed through the slot 18d tangentially into theupper portion of the lower chamber. The rate of fluid entry into thelower chamber is regulated by the size of the slot and pressure of thepulp in the lower portion of the upper chamber 14. That is the fluidwhich enters the lower conical separating chamber 16 will be directed ina spiral motion and the volume of fluid entering said chamber iscontrolled by the dimensions of the slot 18d.

In the form shown, the size of the slot 18d can be adjusted during theoperation of the separator. This can be accomplished in a number ofways. The adjustment means illustrated consists in a longitudinallyadjustable generally cylindrical sleeve portion 19 which is connected tothe upper end of the tapered shell forming the lower chamber 16. Thecylindrical portion 19 is vertically adjustable within the cylindricalside wall portion 18a of baffle 18 by means of a threaded connectiontherewith thereby varying the length of slot 18d. An internally threadedsleeve member fixed to the lower portion of mounting plate is providedto permit full length opening of slot 18d while still providing supportfor the shell of the lower chamber 16. Suitable handles 19a may beprovided for assisting in the rotational adjustment of said lower shellportion.

In operation, the fluid pulp material containing speck type impurities,flows through pipe 20, valve 22, into the upper end of upper inletchamber 12 through the tangential opening 26 to produce the desiredcyclonic rotation of the pulp within the upper separating chamber 14 ofthe hydrocyclone cleaning apparatus. The rotating fluid pulp flowsdownwardly as a result of the operation of gravitational force and theparticles of heavier density accumulate near the side wall of the upperchamber 14 as a result of centrifugal force. As the chamber 14 istapered in a conical shape in the downward direction, the volume of pulpaccommodated at the top of the chamber 14 does not have suffrcient roomat the bottom of the chamber. Therefore, the fluid tends to rotationmore rapidly as it travels downwardly and inwardly in the chamber andthe fluid near the center of rotation is forced upwardly to theacceptable pulp outlet 48 throughout the length of the chamber. Theheavy body impurities, however, are retained near the outer wall andtravel the entire length of the upper chamber 14 in a downward spiralpath and are admitted to the lower chamber 16 through the tangentiallydirected slot 18d in the baffle 18 while maintaining the cyclonicrotational movement thereof.

Most of the acceptable pulp in the original feed pulp is carried away asa result of the separating action in the first chamber and as a resultonly pulp containing a relatively high concentration of impurities isintroduced into the lower chamber 16. It has been found that theappropriate rotational velocities and rate of passage of fluid through aconical separation chamber when impurities are relatively concentratedmust be different from that when impurities are relatively lessconcentrated. In the first chamber 14, of this embodiment of myinvention, the inlet pulp feed rate is controlled by valve 22 and thepressure drop between the inlet 26 and the outlet 28 is controlled byvalve 30, the differential pressure between the inlet feed pulp and theoutlet of acceptable feed pulp determining the rate of passage of fluidthrough the chamber. The operator of this hydrocyclone separator willadjust the fluid pressure and the rate of flow thereof through the firstchamber so that conditions are optimum for efficient separation ofaccepts from rejects in the concentration of original feed pulp. Thebaffle 18 acts to control the rate of fluid flow from the first chamber14 to the lower chamber 16. The inlet slot 18d controls the rotationalvelocity and volume of the pulp entering the chamber 16. The rate offlow and pressure of fluid pulp in the chamber 16 is controlled by thedimensions of the inlet slot 18d, the reject discharge orifice 17 in thechamber 16 and the valve 36 on the acceptable pulp outlet of the chamber16. Thus, in the operation of the unit illustrated, the size of thebottom orifice 17 and the slot 18d and the setting of the valves 22, 36and 30, can be used to regulate the fluid flow characteristics in thetwo chambers respectively to produce optimum separation characteristicsin both chambers. Q

It will be appreciate that I have provided an improved single stagehydrocyclone pulp cleaner having two chambers. A substantial benefit ofthis invention is that the quantity of bottom reject material is reducedto the point where a further stage of cleaning of the pulp is notrequired and the reject material may be treated as waste. Thissubstantially reduces the cost of pulp cleaning by eliminating thecapital expense and cost of operating a second stage of cleaners andassociated dumping machinery which is presently conventionally used forreclaiming acceptable pulp from a pulp material having an unacceptablecontent of rejects.

It will, of course, be understood that various changes may be made inthe form, details, arrangement and proportion of the parts withoutdeparting from the scope of the invention, which generally stated,consists in the matter set forth in the accompanying claims.

What is claimed is:

1. A hydrocyclone pulp cleaner for separating impurities from wood pulpcomprising, as a single stage cleaning unit,

a baffle member,

a casing portion defining with said baffle member a first conicalchamber having a pulp inlet at the upper large diameter end thereof,said inlet disposed so that cyclonic rotational movement is produced inthe pulp being supplied to said chamber, and having a centrally disposeddischarge conduit at the large diameter upper end thereof for removingacceptable pulp therefrom,

a casing portion defining with said baffle member a second conicalchamber connected to the lower end of the first chamber and having afinal reject outlet opening at the bottom thereof,

said baffle member disposed between said first and second chambershaving passage means at the outward portion thereof permitting pulp toflow from a position near the side wall of the bottom of the firstchamber into the top of the second chamber in a manner to producerotational cyclonic movement in the body of pulp discharged into saidsecond chamber, and a central conduit section in the upper portion ofsaid second chamber for removing the acceptable pulp therefrom, and

means for adjustably varying the differential pressure between the pulpinlet and at least certain of said pulp discharge outlets of thecleaning unit to regulate the pulp flow conditions in said unit.

2. Structure set forth in claim 1 and said baffle comprising an invertedcup-shaped member having a generally cylindrical side wall portion witha tangentially directed opening formed therein to tangentially dischargeinto the upper portion of the second chamber, the portion of the pulpcirculating in close association to the lower inside wall surface of thefirst chamber.

3. Structure set forth in claim 2 and means for varying the size of thedischarge opening in said baffle side wall.

4. Structure set forth in claim 3 and said means comprising an axiallyadjustable valve member mounted adjacent said opening and adjustablyprojectable longitudinally thereof for varying the length of saidopening.

5. Structure set forth in claim 3 and valve means for varying the flowof pulp through said inlet and the discharge conduits from the twochambers.

6. Structure set forth in claim 4 and said valve member comprising theupper portion of the casing defining the second chamber, said casinghaving a threaded connection with the side wall of said baffle memberwhereby rotation of the casing projects the upper portion thereofupwardly and downwardly to vary the length of said opening.

7. Structure set forth in claim 1 and valve means for controlling theflow through said central discharge conduit connected to the firstchamber to adjust the back pressure of the acceptable material flowingfrom said first chamber.

8. The structure set forth in claim 7 and valve means for controllingthe flow of pulp through the pulp inlet at the upper end of the firstchamber.

9. Structure set forth in claim 8 and valve means for controlling theflow of acceptable pulp through the central conduit section in the upperportion of said second chamber.

1. A hydrocyclone pulp cleaner for separating impurities from wood pulpcomprising, as a single stage cleaning unit, a baffle member, a casingportion defining with said baffle member a first conical chamber havinga pulp inlet at the upper large diameter end thereof, said inletdisposed so that cyclonic rotational movement is produced in the pulpbeing supplied to said chamber, and having a centrally disposeddischarge conduit at the large diameter upper end thereof for removingacceptable pulp therefrom, a casing portion defining with said bafflemember a second conical chamber connected to the lower end of the firstchamber and having a final reject outlet opening at the bottom thereof,said baffle member disposed between said first and second chambershaving passage means at the outward portion thereof permitting pulp toflow from a position near the side wall of the bottom of the firstchamber into the top of the second chamber in a manner to producerotational cyclonic movement in the body of pulp discharged into saidsecond chamber, and a central conduit section in the upper portion ofsaid second chamber for removing the acceptable pulp therefrom, andmeans for adjustably varying the differential pressure between the pulpinlet and at least certain of said pulp discharge outlets of thecleaning unit to regulate the pulp flow conditions in said unit. 2.Structure set forth in claim 1 and said baffle comprising an invertedcup-shaped member having a generally cylindrical side wall portion witha tangentially directed opening formed therein to tangentially dischargeinto the upper portion of the second chamber, the portion of the pulpcirculating in close association to the lower inside wall surface of thefirst chamber.
 3. Structure set forth in claim 2 and means for varyingthe size of the discharge opening in said baffle side wall.
 4. Structureset forth in claim 3 and said means comprising an axially adjustablevalve member mounted adjacent said opening and adjustably projectablelongitudinally thereof for varying the length of said opening. 5.Structure set forth in claim 3 and valve means for varying the flow ofpulp through said inlet and the discharge conduits from the twochambers.
 6. Structure set forth in claim 4 and said valve membercomprising the upper portion of the casing defining the second chamber,said casing having a threaded connection with the side wall of saidbaffle member whereby rotation of the casing projects the upper portionthereof upwardly and downwardly to vary the length of said opening. 7.Structure set forth in claim 1 and valve means for controlling the flowthrough said central discharge conduit connected to the first chamber toadjust the back pressure of the acceptable material flowing from saidfirst chamber.
 8. The structure set forth in claim 7 and valve means forcontrolling the flow of pulp through the pulp inlet at thE upper end ofthe first chamber.
 9. Structure set forth in claim 8 and valve means forcontrolling the flow of acceptable pulp through the central conduitsection in the upper portion of said second chamber.